Melatonin is a supplement that is widely used to help sleep, but it may make bones stronger in old rats. This comes from new research by McGill University that seems to show that this could make a difference to those at risk of osteoporosis.

Hormones are an essential part of our bone building ability: oestrogen breaks down old bone but it is progesterone that is needed to build new bone. Bones are broken by the body at night as we sleep. However, as we age, we sleep less, and so the cells that break down the bones are more active and so more bone is broken down and lost. This was not a human trial, but giving old rats melatonin supplements to regulate their circadian rhythms and sleeping pattern, the researchers have been able to make their bones denser, less brittle and more flexible. The researchers found that there was a significant increase in both bone volume and density among the rats that had received melatonin supplements.

The amount of melatonin we produce is determined by how dark or light our surroundings are. Our eyes have specialized light-sensitive receptors that relay this message to a cluster of nerves in the brain which sets our internal biological clock, also called our circadian rhythm, which regulates a variety of body functions including sleep.

Melatonin is made from an amino acid called tryptophan. When our surroundings are dark, the SCN tells the pineal gland to produce melatonin, which is thought to trigger sleep. Some melatonin is also made in the stomach and intestines.

Next step is to explore whether melatonin supplements prevent bone breakdown or can actually repair damage and the researchers are pursuing funding to undertake human trials.

What you need to know about melatonin

If you’re considering taking melatonin supplements, check with your doctor first — especially if you have any health conditions. The correct dose depends on the intended use. For example, circadian rhythm sleep disorders are often treated with 0.5 milligrams of melatonin a day, while doses of 3 to 5 milligrams a day might be used to treat jet lag or reduce the time it takes to fall asleep.

Melatonin is generally recommended only for short-term use — up to two months. The most common melatonin side effects include:

• Daytime sleepiness
• Dizziness
• Headaches

Other, less common melatonin side effects might include abdominal discomfort, mild anxiety, irritability, confusion and short-lasting feelings of depression.

Melatonin supplements can interact with various medications, including:

• Blood-thinning medications (anticoagulants)
• Medications that suppress the immune system (immunosuppressants)
• Diabetes medications
• Birth control pills

Reducing your risk

If you are at risk for osteoporosis it makes sense to strengthen your bones with weight bearing exercise, a healthy diet and good progesterone levels. High levels of oestrogen (oestrogen dominance) can upset the bone building balance leaving your bones fragile, brittle and when established the bones can have a lace-like appearance where the bone has not been renewed.